Molto Benne

I haven't done Hirakata Park before so cant comment on it, but I'd make the mission out to Nagashima. Hakugei is my number 1, and I think Steel Dragon gets overly criticised compared to other Gigas, its insane. If you get a reasonably quiet (and not windy) day its a great park. Been twice, longest I waited was 45 mins for Hakugei, skip the lines available if needed. Second what others are saying, the queues for Disney and Universal are pretty similar, in my experience Universal was probably worse. Disney are much better at theming the queues too, much less cattlepen feeling. If thrills are the only concern, go universal, but I'd strongly suggest checking DisneySea at least. Also depending how many days you have in Tokyo, try spare an hour at Tokyo Dome City and get Thunder Dolphin and Panic Coaster. Stupidly easy to get to from the metro lines, every time I've gone Thunder dolphin hasn't had a queue.